The decision came after an impassioned and at times highly personal debate at the City Council that highlighted the backlash the smokeless cigarettes have generated as their popularity grows.

Critics warn that the electronic devices, which produce a nicotine-laced vapor inhaled by users, could pave the way for a resurgence in tobacco use among young adults.

Dr. Jonathan Fielding, director of the Los Angeles County Department of Public of Health, said the growing acceptance of "vaping"-- as e-cigarette use is known -- threatens to undermine decades of public education efforts aimed at stigmatizing smoking.

Other e-cigarette opponents said they do not want to risk the possibility that the secondhand vapor will be found to be harmful.

"We have a right to ... choose to breathe clean air," Councilwoman Nury Martinez told her colleagues. "And if this device turns out to be safe, then we can always undo the ordinance. But if this device proves not to be safe, we cannot undo the harm this will create on the public health."

Five states and the District of Columbia have already included e-cigarettes in anti-smoking bans or moved to restrict where they can be used. Last year, New York City passed an ordinance applying traditional anti-smoking rules to e-cigarettes and Chicago recently moved to prohibit vaping in bars, restaurants and most indoor public places.

The e-cigarette crackdown has come "much faster than what happened with smoke-free ordinances," said Tim McAfee, director of the federal Centers for Disease Control's Office on Smoking and Health, which has yet to release data on the potential harm of secondhand vapors.

Los Angeles' decision means that within weeks, e-cigarettes users will have to camp out with smokers relegated to sidewalks outside their jobs and smoking porches at bars and nightclubs. The devices will be permitted in vaping lounges, where customers can sample flavored e-cigarette liquids. But they will be outlawed in outdoor dining areas of restaurants and at city-sponsored farmers' markets. Geraldine Monroy, who works at Downtown Vape, said she doesn't use e-cigarettes in restaurants out of respect for other customers. But she voiced dismay that vaping will be outlawed in bars.

If e-cigarette users are forced outside, "you leave your friends, you leave the excitement," she said. "Regulating them would take away a lot of the enjoyment we have in smoking them."

Cities are acting but, at the federal level, e-cigarettes are still treated far differently than tobacco products. Americans haven't seen a cigarette ad on TV for decades. But e-cigarette manufacturer NJOY -- which hired lobbyists to influence the outcome of Tuesday's council vote -- has run spots during the Super Bowl, one of the most watched television events of the year.

"You know what the most amazing thing about this cigarette is?" says the narrator in one NJOY ad. "It isn't one."

That is the argument made by Jeff Stier, a senior fellow with the National Center for Public Policy Research, a conservative think tank focused on free market policies. The push by cities to restrict e-cigarettes limits access to an alternative to smoking -- and could have the unintended effect of slowing progress on public efforts to combat harmful tobacco use, he said.

"Within a decade, e-cigarette sales will outpace cigarette sales," he said. "I think that's a victory for public health that we should not get in the way of."

The long-term health effect of vapor on those who are in close proximity to e-cigarette users remains unclear. The lack of federal data on the question has given ammunition to supporters of e-cigarettes who assert that the council is acting prematurely. Tuesday's City Hall debate quickly turned personal. Councilman Mitch O'Farrell, who pushed for the new restrictions, recalled his days breathing secondhand smoke as a waiter in a downtown restaurant. Martinez, who sided with O'Farrell, described her husband's unsuccessful battle to quit smoking.

Councilman Joe Buscaino led an unsuccessful attempt to exempt bars and nightclubs from the ban, a measure sought by lobbyists for the e-cigarette industry. He too invoked a family member while making his arguments.

E-cigarettes "are not tobacco," he said. "I don't think they should be regulated exactly the same way. And I've heard from so many people, including my cousin Anthony, that they've stopped smoking from the help of e-cigarettes."

Buscaino's bid to allow the devices in 21-and-older establishments was supported by five other council members: Bob Blumenfield, Mitchell Englander, Felipe Fuentes, Curren Price and Paul Krekorian.

But Council President Herb Wesson balked at the exemption, telling lawmakers that he has been hooked on cigarettes for nearly 40 years -- and will probably die because of them.

Calling himself "the council's No. 1 smoker," Wesson said he took up the habit as a 20-year-old factory worker because he wanted to be "cool."

"I'm telling you, the high percentage of kids that smoke, smoke because it's cool. And when you're 15 you want to be cool," he said. "I will not support anything -- anything -- that might attract one new smoker."

Some council members expressed frustration at the lack of research on the effects of e-cigarette vapor. Manuel Suarez Jr., owner of Golden State Vape Shop, said fear about the devices is based on misunderstanding.

"We cater to people who've been smoking for over 20 years," he said. "We're here to help them quit."